JP2008134600A - Electrooptic device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic device that allows detection of a position specified on its display screen while having a simple configuration. <P>SOLUTION: The electrooptic device is equipped with a plurality of first scan lines, second scan lines with the number identical to that of the first scan lines, a plurality of signal lines disposed so as to intersect the respective first scan lines and the second scan lines, and a plurality of pixels disposed at intersections of the first scan lines and the second scan lines and the signal lines. Each pixel located in an i-th row and a j-th column includes a first transistor, a second transistor, and a pixel electrode. The plurality of pixels are formed in a matrix. A gate of the first transistor is coupled to the first scan line in the i-th row. One of a source and a drain of the first transistor is coupled to the signal line on the j-th column. A gate of the second transistor is coupled to the second scan line in the i-th row. One of a source and a drain of the second transistor is coupled to the other of the source and drain of the first transistor (the source of the first transistor). The other of the source and drain of the first transistor (the source of the first transistor) is coupled to the pixel electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electro-optical device such as an electrophoretic display device or a liquid crystal display device. More particularly, the present invention relates to an electro-optical device that can display and write information.

  An electro-optical device such as an electrophoretic display device or a liquid crystal display device is used for a display unit of an electronic apparatus that can replace a conventional paper medium such as so-called electronic paper or electronic book. As such a conventional electro-optical device, for example, JP 2005-24864 A (Patent Document 1), JP 2005-283820 A (Patent Document 2), JP 2005-84343 A (Patent Document 3). Etc. are disclosed. These conventional electro-optical devices merely display data stored in a memory in advance (for example, image data such as books and photographs). That is, the conventional electro-optical device is only used for display, and it is difficult for the user to freely write a memo, an underline or the like in the display image, or to specify a desired position in the image. There was.

Japanese Patent Laid-Open No. 2005-24864 JP 2005-283820 A JP 2005-84343 A

  In view of the above-described problems, an object of the present invention is to provide an electro-optical device that is a display device and also functions as an information collecting device. Specifically, an object of the present invention is to provide an electro-optical device capable of detecting a designated position on a screen with a simple configuration and enabling handwriting input on a display screen of an electro-optical device such as electronic paper.

  The present invention relates to an electro-optical device having an image display period and an information collection period. The electro-optical device of the present invention includes at least a panel unit and a data processing unit, and the panel unit includes a first substrate, a second substrate, and an electro-optical material, and an electric circuit is provided between the first substrate and the second substrate. An optical material is sandwiched. On the first substrate, a plurality of first scanning lines, a plurality of second scanning lines arranged in parallel to the first scanning lines, a plurality of signal lines intersecting the first scanning lines and the second scanning lines, Pixels arranged at intersections of the first scanning line and the second scanning line and the signal line are provided. A plurality of pixels are formed in a matrix on the first substrate. Each pixel located in i rows and j columns (i and j are both natural numbers) includes a first transistor, a second transistor, and a pixel electrode. In the present invention, the gate of the first transistor is connected to the i-th first scanning line, one of the source and drain of the first transistor is connected to the signal line of the j-th column, and the gate of the second transistor is connected to the i-th row. Connected to the second scanning line of the eye, one of the source or drain of the second transistor is connected to the other of the source or drain of the first transistor, and the other of the source or drain of the first transistor is connected to the pixel electrode. It is characterized by being.

  Further, the present invention is characterized in that the other of the source and the drain of the second transistor is connected to the reference power source. Since the first scanning line in the (i-1) th row can be used as the reference power source, in this case, the other of the source and the drain of the second transistor is connected to the first scanning line in the (i-1) th row. Also good. The present invention is also characterized in that a storage capacitor is provided between the other of the source or the drain of the first transistor and the reference power supply. When the first scanning line in the (i-1) th row is used as the reference power source, a storage capacitor is provided between the other of the source or drain of the first transistor and the first scanning line in the (i-1) th row. Features.

  In the present invention having the above circuit configuration, the first substrate is transparent, the second substrate is formed with a common electrode, the pixel electrode is formed of a transparent conductive film, and the first substrate, the second transistor, A light-shielding film is arranged between the two. When the storage capacitor is provided, as described above, the first substrate is transparent, the second substrate is formed with a common electrode, the pixel electrode is formed of a transparent conductive film, and the first substrate and the second transistor are formed. And a storage capacitor is a storage capacitor dielectric film sandwiched between the storage capacitor first electrode, the storage capacitor second electrode, and the storage capacitor first electrode and the storage capacitor second electrode. The storage capacitor first electrode, the storage capacitor second electrode, and the storage capacitor dielectric film are both transparent. The pixel electrode may also serve as the storage capacitor second electrode. The light shielding film is provided at a position overlapping the active region of the second transistor. On the other hand, this light shielding film is also characterized in that it is provided at a position that does not overlap with the active region of the first transistor.

  In the present invention having the above-described circuit configuration and cross-sectional structure, a first scan having a function of selecting a specific first scan line from a plurality of first scan lines connected to the first scan line on the first substrate. A line selection circuit; a second scanning line selection circuit connected to the second scanning line and having a function of selecting a specific second scanning line from the plurality of second scanning lines; and a plurality of terminals connected to one end of the signal line A display signal supply circuit having a function of supplying a display signal specific to each signal line to each of the signal lines, and each signal line connected to the other end of the signal line and output from each of the plurality of signal lines. A sensor signal reading circuit having a function of reading a unique sensor signal is also formed. Further, according to the present invention, the data processing unit includes an input unit, a control unit, and a storage unit, and the input unit has a function of supplying display image information input from the outside to the control unit or the storage unit. Has at least a function of controlling the first scanning line selection circuit, the second scanning line selection circuit, the display signal supply circuit, the sensor signal readout circuit, and the storage unit, and the storage unit is the description image information based on the display image information and the sensor signal. It has the function to memorize. The control unit has a function of creating a new display image using the display image information and the description image information, and supplying the new display image to the display signal supply circuit as a new display signal. Furthermore, the present invention is characterized in that a switching circuit for switching conduction or non-conduction between the signal line and the display signal supply circuit is provided between the signal line and the display signal supply circuit. This switching circuit makes the signal line and the display signal supply circuit conductive during the image display period, and makes the signal line and the display signal supply circuit non-conductive during the information collection period.

  The electro-optical material used in the present invention is also characterized by being an electrophoretic material, a liquid crystal material, or an electrochromic material.

  The present invention also features an electronic apparatus including the electro-optical device described in any one of the above items.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The electro-optic material used in this embodiment is an electro-effect display material that changes its display according to an electric field, such as an electrophoretic material or a liquid crystal material, or an electro-optical material that is displayed according to an electric current, such as an electrochromic material or an organic electroluminescence material. It is a current-driven display material that changes the current. When the electrolytic effect type display material is used, various displays are made possible by sandwiching the electrolytic effect type display material between the pixel electrode and the common electrode and applying a predetermined electric field between these electrodes. On the other hand, when a current-driven display material is used, a current-driven display material (for example, an electrochromic material, hereinafter referred to as an electrochromic material and a display device using the same) is referred to as an ECD between the pixel electrode and the common electrode. And a predetermined current is passed between these electrodes, or a circuit for controlling a current source is connected to the pixel electrode, and a current-driven display material (for example, an organic electro-electric display material) is connected between the current source and the common electrode. Various displays are possible by sandwiching a luminance material, hereinafter referred to as an organic electro-luminance material and a display device using the same, and passing a predetermined current. The present embodiment is universally usable regardless of which electro-optic material is used, and therefore, the present invention will be described in detail below by taking an electrophoretic material as an example of the electro-optic material. Therefore, in the following description, an electrophoretic display (EPD) is an example of the electro-optical device of the present invention.

  The present embodiment relates to an electro-optical device (hereinafter abbreviated as this device) having an image display period and an information collection period. The image display period refers to a period during which the apparatus spends displaying one-screen display image information input from the outside in the form of an electrical signal or electromagnetic wave signal on the functional plane of the apparatus, and is also referred to as an image display frame. . During this period, the device functions as a display device. The image display frame corresponds to one frame in a normal display device. On the other hand, the information collection period refers to a period during which the functional plane is a flat sensor, and is also referred to as an information collection frame. During this period, the device functions as an information collecting device, and sensor information for one screen is collected. For example, a part of a period during which the user of this apparatus inputs information by spatially moving an input device on the functional plane is an information collection period. When a pen-type light irradiation device is used as the input device, the user can specify a specific position on the functional plane during this period, and handwriting input is possible by combining the image display period and the information collection period. It becomes. The device is thus an ordinary electrical display device (for example an electronic book) and at the same time an electrical writing device (for example an electronic notebook).

  1 and 2 show a circuit configuration of the electro-optical device according to the present embodiment. The apparatus includes at least a panel unit and a data processing unit. The panel unit includes a first substrate, a second substrate, and an electro-optic material, and the electro-optic material is sandwiched between the first substrate and the second substrate. Is done. 1 and 2 illustrate a first substrate 60 and a data processing unit 34 that form part of the panel unit. On the first substrate 60, the plurality of first scanning lines 10, the plurality of second scanning lines 12 arranged in parallel to the first scanning lines 10, and the first scanning lines 10 and the second scanning lines 12 intersect. A plurality of signal lines 14 and pixels 16 disposed at the intersections of the first scanning lines 10 and the second scanning lines 12 and the signal lines 14 are provided. A plurality of pixels are arranged in a matrix on the first substrate 10 to form a pixel portion. In the example of FIG. 2, a plurality of readout lines 15 arranged in parallel with the signal line 14 are also provided. In this example, since all the pixels have an image display function and an information input function, the number of the first scanning lines 10 and the number of the second scanning lines 12 are the same. In the example of FIG. 14 and the number of readout lines 17 are the same. However, when the number of pixels having the image display function is different from the number of pixels having the information input function, the number of the first scanning lines 10 and the second scanning lines 12, the signal lines 14 and the readout lines 15 It is not necessary to match the number of

  FIGS. 3 and 4 are circuits showing the detailed configuration of each pixel corresponding to FIGS. 1 and 2, respectively, showing pixels located in i rows and j columns (i and j are both natural numbers). Each pixel 16 includes a first transistor 40, a second transistor 42, and a pixel electrode 48. Both the first transistor 40 and the second transistor 42 are thin film transistors (TFTs). Here, the present invention is described using an example in which an image is displayed on an electrophoretic display (EPD) during an image display period. Therefore, the first transistor 40 that plays the role of a pass gate for a display signal is also called an EPD switching TFT. There is. Similarly, a light irradiation device is taken as an example of an input device for handwritten input during an information input period, and it is assumed that each pixel detects light. Therefore, the second transistor 42 that identifies a pixel that detects light is used as a photo. It is also called a sensor switching TFT. The first scanning line 10 that controls the on / off state of the first transistor 40 is also called an EPD scanning line, and the second scanning line 12 that controls the on / off state of the second transistor 42 is also called a photosensor scanning line. In the present embodiment, in the pixel in i row and j column, the gate (G) of the first transistor 40 is connected to the first scanning line 10 in the i row, and the source (S) or drain (D) of the first transistor 40. ) Is connected to the signal line 14 in the j-th column. Strictly speaking, since the relationship between the source and drain of a transistor can be exchanged according to an input signal, one of the two terminals cannot be determined as a source or drain. Here, however, for convenience of explanation, one is called a drain and the other is called a source. 3 and 4, the drain of the first transistor 40 is connected to the signal line 14 in the j-th column. Further, in the present embodiment, the gate of the second transistor 42 is connected to the second scanning line 12 in the i-th row, and one of the source and the drain of the second transistor 42 (the drain of the second transistor) is the source of the first transistor 40. Alternatively, the other of the drains (the source of the first transistor) is connected, and the other of the sources or the drains of the first transistor 40 (the source of the first transistor) and the pixel electrode 48 are connected. The other of the source and the drain of the second transistor 42 (the source of the second transistor) is connected to a reference power supply. The reference power source may be a high voltage source (for example, a so-called positive power source such as 3.3 V or 5 V) or a low voltage source (for example, a so-called negative power source such as 0 V). Unlike the example of FIG. 3, a dedicated reference power supply line may be provided for each row or every two rows. However, as shown in the example of FIG. It is also possible to use the line (the first scanning line of the adjacent pixel). In this case, the other of the source and the drain of the second transistor 42 (the source of the second transistor) is the first scanning line of the i−1th row. 10 is connected. As a result, the reference power supply becomes the first scanning line potential in the non-selected state. When an N-type transistor is employed as the first transistor 40, the source of the second transistor 42 is connected to a low voltage source during the non-selection period of the pixel. On the other hand, as shown in FIG. 4, when the readout line 15 unique to each pixel is provided, the reference power source is a high voltage source or a low voltage source. An ammeter is provided at the tip of the readout line 15, and a high voltage source or a low voltage source is present at the tip. When the high voltage source is connected to the tip of the ammeter, the signal line 14 in the j-th column is connected to the low voltage source during the information collection period. On the contrary, when the low voltage source is connected to the tip of the ammeter, the signal line 14 in the j-th column is connected to the high voltage source during the information collecting period. In any case, the source of the second transistor 42 is connected to the reference power source of the high voltage source or the low voltage source via the readout line 15 and the ammeter.

  With this configuration, the present device becomes a display device capable of handwriting input, and the principle will be described here. A display device capable of handwriting input means that one pixel has a function of displaying an image during an image display period and a function of collecting information that light is detected during an information collection period. To do. First, all the second scanning lines 12 are set in a non-selected state during the image display period. The non-selected state of the scanning line is a state in which the transistor to be controlled by the scanning line (here, the second transistor 42) is not selected. For example, an N-type TFT is employed for the corresponding transistor (second transistor 42). If it is, the scanning line (second scanning line 12) is in a low potential state (the second scanning line is connected to a low voltage source). When the second transistor 42 is in a non-selected state (the second transistor 42 is in a high-resistance off state), each pixel can control the pixel electrode potential using the first transistor 40, so that the conventional liquid crystal display It functions as a normal display device like (LCD) and EPD. On the other hand, during the information collection period, each pixel becomes a photodetector. In this case, all the first scanning lines 10 are set to a non-selected state, and the first transistors 40 of all the pixels are turned off. When the transistor is in an off state, the transistor generates a light leakage current in accordance with the intensity of light applied to the transistor. When light is not irradiated, the off-state current of the transistor (source-drain current in the off state) is very small. However, when intense light is irradiated, the off-state current increases remarkably due to light leakage current. This is because when the transistor is in the off state, the drain end of the transistor (the term “drain end” here is used in a physically correct sense), and the drain used in the description of FIGS. This is because a PN junction is electrically formed and does not necessarily match, and this PN junction functions as a photodiode. In the present embodiment, this characteristic is positively utilized, and the transistor (first transistor) that determines whether or not the display signal can pass is used as a photosensor for determining the illuminance of strong light during the information collection period during the image display period. is there. Specifically, all the first scanning lines 10 are set in a non-selected state, and all the first transistors 40 are turned off. The second scanning line 12 is sequentially selected in a state where the first transistor 40 becomes a photosensor, and the second transistor 42 controlled by the selected second scanning line 12 is turned on. In this case, the signal line 14 is connected to the reference power source via the first transistor 40 functioning as a photosensor and the second transistor 42 that is turned on, and the first transistor 40 is irradiated with light. The amount of current generated between the signal line 14 and the reference power supply changes according to the strength. This change is detected, and the light irradiation amount to the pixel is measured. In short, if the pixel selected by the second scanning line selection circuit 20 and the sensor signal readout circuit 26 is irradiated with strong light, the light leakage current in the first transistor 40 increases, so that a large current is detected. Is done. On the other hand, if the pixel selected by the second scanning line selection circuit 20 and the sensor signal readout circuit 26 is not irradiated with light, the light leakage current in the first transistor 40 hardly occurs, and the current is very weak. It will only be detected. Thus, in this apparatus, each pixel displays an image during the image display period, and detects the amount of light irradiation during the information collection period.

  In the present embodiment, a storage capacitor is provided between the other of the source and the drain of the first transistor 40 (the source of the first transistor) and the reference power supply so that the image displayed during the image display period is of high quality. May be. By providing the storage capacitor, image quality improvement such as an increase in the contrast ratio of the EPD or an increase in the number of display gradations of the LCD is realized. As described above, when the first scanning line 10 in the (i-1) th row is used as the reference power supply (FIG. 3), the other of the source or the drain of the first transistor 40 (the source of the first transistor) and the i-1th row. A holding capacitor 46 is provided between the first scanning line 10 of the eye. Since the storage capacitor 46 needs to be connected to a fixed power supply during a period in which the display signal is maintained in the pixel (non-selection period of the pixel), a reference power supply having a high potential or a low potential is provided as shown in FIG. In the case of passing through the readout line, a storage capacitor 46 is provided between the other of the source and drain of the first transistor 40 (the source of the first transistor) and the first scanning line 10 in the (i−1) th row. Is desirable. When the first scanning line 10 in the (i-1) th row is used as the reference power supply, it is not necessary to provide the reference power supply line again. Therefore, the aperture ratio (the ratio of the pixel electrode area contributing to display to the pixel area) in the pixel is set. Enhanced. Of course, a separate wiring may be provided as necessary, and the other of the source and the drain of the second transistor (the source of the second transistor) and the storage capacitor may be connected to the wiring. In FIG. 3, the first scanning line 10 that controls adjacent pixels is also used as the reference power supply line.

  Next, the cross-sectional structure of this apparatus will be described with reference to FIG. In the present embodiment, since the first transistor is used as a photosensor during the information collection period, light needs to reach the first transistor during this period. When an electro-optic material is sandwiched between the first substrate and the second substrate and viewed from the second substrate side (from the top of FIG. 5), the display device displays black and emits light. In the state of being blocked, light does not reach the first transistor fabricated on the first substrate from the second substrate side. If an electro-optical material such as ECD or EPD that is not transparent is used, light does not reach the first transistor from the second substrate side regardless of display. Therefore, in this apparatus, the display device is viewed from the first substrate side. In this apparatus in which the electro-optic material is sandwiched between the inner side of the first substrate and the inner side of the second substrate, the outer surface of the first substrate is a functional plane, and the user is from the outer side of the first substrate (from the lower side of FIG. 5). This device is viewed or handwritten input is performed. By doing so, the image display function and the information collecting function are compatible with each other regardless of the display contents and the type of electro-optic material. Specifically, a backlight serving as a light source in the case of LCD is placed outside the second substrate, and in the case of organic EL, light is emitted to the first substrate side (so-called bottom emission type). In the present embodiment having the circuit configuration described in detail above, the first substrate is therefore transparent to visible light, and a transparent glass substrate, a plastic film made of a transparent resin material, or the like is used. On the other hand, special transparency is not required for the second substrate. The second substrate may be transparent or non-transparent glass or film, or may be paper or fiber, a semiconductor substrate, a metal plate, or the like.

  As shown in FIG. 5, the electro-optical device according to the present embodiment includes a transparent first substrate 60, a second substrate 68 disposed to face the first substrate 60, and an electro-optical device sandwiched between the pair of substrates. Material 52. A circuit layer 62, a light shielding film 64, and a pixel electrode 48 are disposed on the first substrate 60. The light shielding film 64 is disposed at a predetermined position between the first substrate 60 and the circuit layer 62. The pixel electrode 48 is formed on the circuit layer 62 so as to be in contact with the electro-optic material 52. The electro-optic element layer 66 includes a pixel electrode 48, a common electrode 50, and an electro-optic material 52. The common electrode 50 is formed on the inner surface of the second substrate in the electro-optical device (vertical EPD or ECD shown in FIG. 5 or LCD that is not in-plane switching) that generates an electric field or current in a direction perpendicular to the first substrate surface. In an electro-optical device (horizontal EPD, in-plane switching LCD, organic EL, or the like) that generates an electric field or current in the horizontal direction with respect to the first substrate surface, it is formed on the first substrate. In this embodiment, since the electro-optic material is viewed from the first substrate 60 side and the area ratio of the pixel electrode 48 in the pixel is large, the pixel electrode 48 is formed on the first substrate 60 with a transparent conductive film. . Thus, it is possible to see the image displayed from the first substrate 60 side.

  The circuit layer 62 includes the first scanning line 10, the second scanning line 12, the signal line 14, the first transistor 40, the second transistor 42, and the storage capacitor 46. In the structure shown in FIGS. 2 and 4, the circuit layer 62 also includes the readout line 15. As described above, both the first transistor 40 and the second transistor 42 are formed of field effect thin film transistors. In addition to such a configuration, a light shielding film 64 is further disposed between the first substrate 60 and the second transistor 42 in this embodiment. The light-shielding film 64 has a function of shielding visible light. Specifically, a metal film such as aluminum, chromium, or tungsten, or a relatively thick semiconductor film having a thickness of 100 nm to 500 nm is used. It plays the role of blocking light from entering the semiconductor film portion 72 (active region) of the second transistor 42 from the 60 side. On the other hand, the light shielding film 64 must be provided at a position that does not overlap the active region of the first transistor 40. Here, the “active region” means a channel formation region, a drain region in contact with the channel formation region, and a source region in contact with the channel formation region. Since the first transistor 40 functions as a photosensor during the information collection period, it is necessary to irradiate the drain end of the first transistor 40 with light. On the other hand, since the second transistor 42 has a selection function for specifying a desired pixel during the information collection period, it should not malfunction due to light irradiation. Therefore, in this embodiment, the light shielding film 64 is disposed only under the second transistor 42 so that light is not incident on at least the active region of the second transistor 42. As a result, malfunction due to the light of the second transistor 42 is avoided, and the apparatus operates correctly as an information collecting apparatus. Since the purpose of the light shielding film 64 is to prevent malfunction due to the light leakage current of the second transistor 42, the light shielding property does not need to be perfect. It is sufficient to shield the light so that the second transistor 42 does not malfunction. Use of an amorphous or polycrystalline silicon film for the light shielding film 64 is convenient because the circuit layer 62 can be manufactured by a normal TFT manufacturing process. In that case, if the light shielding film 64 has a thickness of 100 nm to 500 nm, the light shielding purpose is achieved. If the light-shielding film 64 is thick, the light-shielding property is increased, but problems such as a large step or peeling of the light-shielding film are likely to occur. Therefore, the thickness of the semiconductor film that becomes the light shielding film 64 is ideally 150 nm to 300 nm.

  When the storage capacitor 46 is provided, it is desirable that all the components of the storage capacitor 46 are transparent. The storage capacitor 46 includes a storage capacitor first electrode, a storage capacitor second electrode, and a storage capacitor dielectric film sandwiched between the storage capacitor first electrode and the storage capacitor second electrode. It is desirable that both the storage capacitor second electrode and the storage capacitor dielectric film are transparent. As described above, in the present embodiment, the outer plane of the first substrate 60 is a functional plane, and the display is viewed from the first substrate 60 side. Therefore, the first substrate 60 is transparent, and the pixel electrode 48 is also formed of a transparent conductive film. The storage capacitor 46 also occupies a relatively large area in the pixel. In particular, in the EPD, the storage capacitor 46 may occupy an area of 50% or more of the entire pixel. In order for the electro-optic material to be seen beautifully when the apparatus is viewed from the first substrate 60 side, it is desirable that the storage capacitor 60 having a large area is also transparent.

  Next, the structure of the circuit layer 62 will be described. The insulating film 70 is a base protective film and is formed on the first substrate 60 so as to cover the light shielding film 64. An island-shaped semiconductor film 72 is formed on the upper surface of the insulating film 70. The semiconductor film 72 may be shared by the first transistor 40 and the second transistor 42 on one island as shown in FIG. 5, or each island may be associated with each transistor. good. The insulating film 78 is a gate insulating film of each transistor, and is formed on the insulating film 70 so as to cover at least the channel formation region of the semiconductor film 72. On the insulating film 78 and above the semiconductor film 72, the first scanning line 10 and the second scanning line 12 are formed. The first scanning line 10 and the second scanning line 12 extend to the semiconductor film 72 and become gate electrodes of the first transistor 40 and the second transistor 42, respectively. The insulating film 80 is a first interlayer insulating film and is formed on the insulating film 78 so as to cover the first scanning line 10 and the second scanning line 12. The signal line 14 and the readout line 15 are formed on the insulating film 80 and are connected to the semiconductor film 72 and the like through contact holes provided in the insulating film 80 as appropriate. Similarly, the wiring 11 is formed on the insulating film 80 and is connected to the semiconductor film 72 and a reference power source (the first scanning line in the (i-1) th row) through a contact hole provided in the insulating film 80 as appropriate. . The insulating film 82 is a second interlayer insulating film, and is formed on the insulating film 80 so as to cover the wiring 11, the signal line 14, and the other wiring 75. One electrode 74 (holding capacitor first electrode) of the holding capacitor 46 is formed on the insulating film 82. The storage capacitor first electrode 74 is connected to the wiring 11 through a contact hole appropriately provided in the insulating film 82. The insulating film 84 is a third interlayer insulating film as well as a storage capacitor dielectric film. The storage capacitor dielectric film is formed on the insulating film 82 so as to cover the storage capacitor first electrode 74 and the wiring 76. As described above, since this apparatus is assumed to be viewed from the first substrate 60 side, each of the insulating films 70, 78, 80, 82, 84 is transparent. In a specific example, a silicon oxide film or a silicon nitride film is used as the insulating film. The pixel electrode 48 formed on the third interlayer insulating film also serves as the storage capacitor second electrode and is formed of the transparent conductive film as described above. In order to connect the pixel electrode to the source of the first transistor, a contact hole is appropriately opened in the third interlayer insulating film to establish connection with the lower layer wiring (here, the wiring 76). The wiring 76 is connected to the wiring 75 through a contact hole provided in the insulating film 82. Thereby, the pixel electrode 48 is electrically connected to the semiconductor film 72 via the wirings 75 and 76. Since both the pixel electrode 48 and the storage capacitor first electrode 74 are preferably transparent conductive films, these electrodes are formed of indium tin oxide ITO or the like, for example. An electro-optic material 52 is formed on the pixel electrode 48 and on the insulating film 84 via an insulating film or the like as necessary. Here, the electro-optic material 52 is an electrophoretic material containing white particles and black particles, and in the following description, the embodiment is described using an example in which white particles are positively charged and black particles are negatively charged. explain. In this example, a second substrate 68 having a common electrode 50 is disposed so as to cover the electrophoretic material 52. The electro-optic element 44 is configured by sandwiching the electro-optic material 52 between the pixel electrode 48 and the common electrode 50. When the common electrode 50 is formed on the second substrate, special transparency is not required, and therefore a non-transparent metal conductive film such as aluminum or a transparent conductive film such as ITO is appropriately used. When the common electrode is formed on the first substrate side, it is preferable to use a transparent conductive film such as ITO.

  In the present embodiment having the circuit configuration and the cross-sectional structure described above, the first scanning line selection circuit 18, the second scanning line selection circuit 20, the display signal supply circuit 22, and the sensor signal readout circuit 26 are formed on the first substrate 60. Is formed (FIGS. 1 and 2). Although these circuits may use an external integrated circuit, they are preferably made of TFTs in the same process as the TFTs forming the pixel portion. The first scanning line selection circuit 18 has a function of connecting to the first scanning line 10 and selecting a specific first scanning line 10 from the plurality of first scanning lines 10. The second scanning line selection circuit 20 has a function of connecting to the second scanning line 12 and selecting a specific second scanning line 12 from the plurality of second scanning lines 12. The display signal supply circuit 22 is connected to one end side of the signal line 14 and has a function of supplying a display signal unique to each signal line 14 to each of the plurality of signal lines 14. The sensor signal readout circuit 26 is connected to the other end side of the signal line 14 (FIG. 1) or the other end side of the readout line 15 (FIG. 2), and is output from each of the plurality of signal lines 14 to 15. A function of reading a sensor signal unique to each signal line 14 and each readout line 15. Specifically, the sensor signal readout circuit 26 includes a selection circuit composed of a shift register, a decoder and the like, and a current comparison circuit (ammeter) composed of an operation amplification circuit and the like, and the signal line 14 or readout line selected by the selection circuit. A weak photosensor signal appearing at 15 is amplified by a current comparison circuit (ammeter) and measured.

  Furthermore, in the present embodiment, the data processing unit 34 includes an input unit 32, a control unit 28, and a storage unit 30. The input unit 32 has a function of supplying display image information input as an electrical signal from the outside to the control unit 28 or the storage unit 30 and also has a function of transmitting various input instructions depending on the user to the control unit 28. . The input instruction is an electric signal that reflects the user's intention expressed by, for example, a direction instruction key (cross key or the like) or a push button, and the input unit 32 also receives such a signal. For example, as will be described later in detail, the apparatus receives a signal for switching between the display mode and the handwriting input mode, and notifies the control unit 28 of this signal. The control unit 28 has a function of controlling at least the first scanning line selection circuit 18 and the second scanning line selection circuit 20, the display signal supply circuit 22, the sensor signal readout circuit 26, and the storage unit 30. The storage unit 30 has a function of storing display image information and description image information based on sensor signals. Described image information is information synthesized based on sensor signals collected by the device during the information collection period, such as handwritten input information written on the functional surface of the device by a user using a pen-type light irradiator, etc. Corresponding to The control unit 28 acquires the data read by the sensor signal reading circuit 26 (hereinafter referred to as “read data”) and stores it in the storage unit 30. Next, the control unit 28 creates description image information based on the read data obtained from one or more information collection periods (information collection frames). Further, the control unit creates a new display image using the display image information stored in the storage unit 30 and the description image information, and supplies the new display image to the display signal supply circuit 22 as a new display signal. It has a function. In response to the input instruction, the control unit 28 selects a circuit that requires an operation from the display signal supply circuit 22, the sensor signal readout circuit 26, the first scanning line selection circuit 18, the second scanning line selection circuit 20, and the like. It also has a function of supplying a necessary signal to the selected circuit and receiving a signal. The storage unit 30 is configured using, for example, a semiconductor memory such as DRAM or SRAM, and stores display image information, read data, description image information, and various data generated or used by the control unit 28. Take on.

  Further, the present embodiment includes a switching circuit 24 between each signal line 14 and the display signal supply circuit 22 when there is no dedicated readout line 15 and the signal line 14 also serves as a readout line (FIG. 1). . The switching circuit 24 includes a pass gate, and switches between conduction and non-conduction between the signal line 14 and the display signal supply circuit 22 based on a control signal supplied from the control unit 28. The switching circuit 24 makes the signal line 14 and the display signal supply circuit 22 conductive during the image display period, and makes the signal line 14 and the display signal supply circuit 22 non-conductive during the information collection period. That is, the switching circuit 24 becomes conductive when the display signal supply circuit 22 writes the display image signal to the signal line 14. On the other hand, when the sensor signal is read out by the sensor signal reading circuit 26, the switching circuit 24 becomes non-conductive.

  This device has the above-described configuration, and is a display device and an information collecting device. Next, the driving method and the usage method will be described with reference to FIGS. 1 to 2 and FIG.

  This apparatus has a display mode in which the functional plane functions as a display device and a handwriting input mode in which a user performs handwriting input on the functional plane. In the handwriting input mode, the functional plane functions as a display device and also functions as a plane sensor. The display mode consists of only one or a plurality of image display periods (image display frames), and the apparatus functions as a display apparatus using these image display frames. In contrast, in the handwriting input mode, the image display period (image display frame) and the information collection period (information collection frame) are alternately repeated, and handwriting input is possible on the display screen. These details will be described below.

(1) Display mode The display mode is composed of one or a plurality of image display frames, and this apparatus becomes a display apparatus during this period. The following operations are performed in this apparatus in each image display frame. First, in the display mode, the control unit 28 completely stops the operations of the second scanning line selection circuit 22 and the sensor signal readout circuit 26. Therefore, the second scanning line selection circuit 22 puts all the second scanning lines 12 into a non-selected state. If the second transistors 42 are N-type, all the second scanning lines 12 are maintained at the lowest potential (for example, 0 V). As a result, all the second transistors 42 are turned off. Further, when the apparatus does not have a dedicated readout line and the signal line 14 also serves as a readout line (FIG. 1), the control unit 28 sets the switching circuit 24 in a conductive state so that the display signal supply circuit 22 and the signal line 14 are connected. Connecting. Display image information obtained from the input unit 32 is stored in the storage unit 30 and converted into display data for each row, and display data corresponding to the selected first scanning line 10 is supplied from the control unit 28 as a display signal. It is transmitted to the circuit 22. Next, the control unit 28 operates the first scanning line selection circuit 18 to select a desired first scanning line 10 from the plurality of first scanning lines 10. If the first transistor 40 is N-type, the highest potential (for example, 5 V) is applied to the first scanning line 10 when selected, and the first scanning line 10 is maintained at the lowest potential (for example, 0 V) when not selected. Display data is supplied to each pixel from the display signal supply circuit 22 via the signal line 14 in a state where the desired first scanning line 10 is selected. Thereafter, the same operation is repeated for the pixels for which display data needs to be supplied to the pixels, and one image display frame is completed (one image display period ends). When a moving image is displayed or an image different from the previous image display frame is displayed on the next image display frame, the same operation as described above is repeated to produce the next image display frame.

  Taking an EPD in which white particles are positively charged and black particles are negatively charged, the operations of the second scanning line selection circuit 20 and the sensor signal readout circuit 26 are completely stopped (thus, all The second scanning line 12 is maintained at the lowest potential (for example, 0 V), and a white image is displayed on the entire screen in the first image display frame in a state where the switching circuit 24 is turned on (referred to as white reset, the entire screen is displayed). It corresponds to erasing white). Then, target display image information is displayed in the next image display frame. The common electrode 50 is given a maximum potential (for example, 5 V) at the time of white reset, and is maintained at a low potential (for example, 0.5 V) when writing display image information to each pixel. The common electrode potential is set to a low potential (for example, 0.5 V) instead of the minimum potential (for example, 0 V) at the time of writing. The common electrode potential is set to the minimum potential (for example, 0 V) during the information collection period. This is because the first scanning line (EPD scanning line) 10 is set to the same potential and the displayed image is maintained during the information collection period. In the image display frame for displaying the target display image information, when the pixel is displayed in black (black writing), the display signal supply circuit 22 gives the highest potential (for example, 5V) to the signal line 14 and displays the pixel in white ( A display signal having the lowest potential (for example, 0 V) is supplied to the signal line 14 during white writing. At this time, the potential of the common electrode 50 is a low potential (for example, 0.5 V).

(2) Handwriting input mode In the handwriting input mode, the image display period and the information collection period are alternately repeated. Hereinafter, the handwriting input mode will be described with reference to FIG. The method of displaying an image on the functional plane during the image display period is the same as the display mode described above. FIG. 14- (1) shows an example of display image information in the K-th order image display period, and text is displayed on the functional plane. The display image information in the K-th image display period is an image displayed in the image display period immediately before the current information collection period starts.

  When the user performs handwriting input on the functional plane of the apparatus, first, an instruction to switch from the display mode to the manual input mode is given. When the input unit 32 receives a signal reflecting such an instruction, the content is transmitted from the input unit 32 to the control unit 28. In response to this, the control unit 28 performs control to switch from the display mode to the handwriting input mode. Specifically, the information collection period is started, and thereafter the image display period and the information collection period are alternately repeated. When the information collection period starts, the control unit 28 stops the operations of the display signal supply circuit 22 and the first scanning line selection circuit 18, and the second scanning line selection circuit 20 and the sensor signal readout circuit 26 that have been stopped during the image display period. And make it work. At the same time, when the switching circuit 24 is present (FIG. 1), the switching circuit 24 is turned off and the display signal supply circuit 22 and the signal line 14 are shut off.

  In the case of an EPD in which white particles are positively charged and black particles are negatively charged, the control unit 28 performs the following image maintenance operation in each circuit in order to maintain the image displayed in the display mode even during the information collection period. To do. As the information collection period starts, the control unit lowers the potential of the common electrode 50 to a low potential (for example, from 0.5) to the lowest potential (for example, 0 V). At the same time, all the first scanning lines 10 are set to the lowest potential, and all the first transistors are turned off. As a result, the storage capacitor, the pixel electrode, and the signal line are completely cut off. Next, all the second scanning lines 12 are once selected and raised to the maximum potential (for example, 5 V). As a result, all the second transistors in the pixel portion are turned on, the reference power supply (in this case, the lowest potential of 0V) and the pixel electrode are brought into conduction, and all the pixel electrode potentials drop to the lowest potential. Although all the pixel electrode potentials are lowered to the lowest potential, the common electrode potential is also lowered to the lowest potential almost simultaneously. Therefore, the pixel electrode and the common electrode are at the same potential, and the image is maintained. If the time difference between the time when the common electrode is lowered to the lowest potential and the time when the pixel electrode is lowered to the lowest potential is 1/10 or less of the response time of the EPD material, particles constituting the EPD material (white particles and black particles) Does not move so the image is preserved. Usually, the response time of EPD material is several hundred milliseconds, so this time difference must be tens of milliseconds or less. Thereafter, based on the control of the control unit 28, the second scanning line selection circuit 20 lowers all the second scanning lines 12 to the lowest potential (for example, 0V), and temporarily turns off all the second transistors 42. . Thus, after the image is maintained, the control unit 28 starts collecting information. That is, each pixel is caused to function as a light detector, and the presence or absence of light irradiation or its illuminance is measured. During the information collection period, the first scanning line selection circuit 18 sets all the first scanning lines 10 to a non-selected state, supplies a scanning signal having the lowest potential (for example, 0 V), and sets all the first scanning lines 10 in the pixel portion. One transistor 40 is turned off. Accordingly, the first transistor 40 plays a role of a photodiode. On the other hand, the second scanning line selection circuit 20 sequentially selects the second scanning lines 12 and turns on the second transistors 42 connected to the selected row. When the second transistor 42 is N-type, the selected second scanning line 12 is supplied with a photosensor scanning signal having the highest potential (for example, 5 V). In a state where a specific second scanning line 12 (for example, the i-th second scanning line) is selected, the signal line 14 in the j-th column is set to a potential opposite to that of the reference power source. For example, if the reference power supply is at a low potential, the signal line 14 is set to a high potential (for example, 5V), and if the reference power supply is at a high potential, the signal line 14 is set to a low potential (for example, 5V). Accordingly, the high voltage source includes an ammeter that forms part of the sensor signal readout circuit 26, a signal line, the first transistor 40 that is off in the pixel that is selected to detect light, and the light source that is also to detect light. The selected pixel is connected to the low voltage source through the second transistor 42 that is in the on state. If the light illuminance at the selected pixel is high, the first transistor 40 generates a light leakage current, and an off-current having a different magnitude is generated according to the light illuminance. The sensor signal readout circuit 26 reads this off-current, and measures the light illuminance at the selected pixel (in this case, the pixel in i row and j column). Thereafter, the sensor signal readout circuit 26 sequentially selects columns and reads out photosensor signals (readout data) from each pixel. The obtained readout data is transferred from the sensor signal readout circuit 26 to the control unit 28 and further stored in the storage unit 30. Thereafter, the sensor signal readout circuit 26 sequentially selects columns, and successively stores readout data obtained from the selected pixels in the storage unit. When reading of one line is completed by the sensor signal reading circuit 26, the process proceeds to the next line. This operation is repeated, and a photo sensor signal (read data) is read from one entire flat sensor in one information collecting period. Depending on the driving method described above, this apparatus becomes an information collecting apparatus that detects light during the image collecting period.

  However, when strong light hits each pixel and the off-state current of the first transistor 40 is large, the pixel electrode potential is shifted from the reference power supply potential set in the image maintenance operation. In order to avoid this, it is sufficient that the on-resistance of the second transistor 42 is sufficiently smaller than the off-resistance when the first transistor 40 is irradiated with strong light. The channel width and channel length of the first transistor 40, the channel width and channel length of the second transistor 42, and the potential in the selected state of the second scanning line 12 (the gate potential for turning on the second transistor) are the first The off resistance when the transistor 40 is irradiated with strong light is set to be 100 times higher than the on resistance of the second transistor 42. As a result, the image is not disturbed during the information collection period.

  Now, when a pen-type light irradiation device is used as the input device, the control unit 28 traces any position on the functional plane (the first substrate 60 outer plane) with the pen-type light irradiation device based on the read data. (That is, the position of the nib) can be determined. In FIG. 14- (2), the position of the pen specified by the flat sensor during the K-th information collection period is shown as an example. The control unit 28 can reflect the pen tip position detection result thus obtained in subsequent information processing. For example, if the display image includes a page feed button for sending an image to the next page and the position is designated by the pen-type light irradiation device, the control unit 28 performs a process of switching the display image to the next page. Do. In addition, when the electro-optical device 1 according to the present embodiment is incorporated into various electronic devices, the control unit 28 can also deliver the position detection result to a higher-level control unit (not shown). This is reflected in the subsequent processing by the upper control unit. As one specific example of the manner in which the contents of instructions given by the user as described above are reflected in subsequent information processing, a method of overwriting the contents of handwritten input in an image will be briefly described below.

  The control unit 28 specifies the position of the pen-type light irradiation device on the functional plane (screen) based on the read data acquired from the sensor signal reading circuit 26 and stored in the storage unit 30 during the K-th order information collection period ( FIG. 14- (2)). Next, description image information to be overwritten on the original (K-order) display image information in the next (K + 1) -order image display period is created using the specified position information of the pen-type light irradiation device. The described image information is display information that reflects information input from the functional plane, and is displayed in the next image display period. Specifically, it corresponds to the content written with a pen-type light irradiation device. In FIG. 14- (3), description image information to be displayed in the (K + 1) -th order image display period is drawn, and pixels corresponding to the pen-type light irradiation device positions are displayed in black. Next, the control unit 28 performs the K + 1 primary display image information with respect to the K + 1 primary display image information (FIG. 14- (5), in this example, the K primary display image information and the K + 1 primary display image information are the same) stored in the storage unit 30. The information is overwritten to produce a display image in the K + 1 primary image display period (FIG. 14- (4)), which is displayed in the K + 1 primary image display period. Thus, the black display pixel in the previous screen (display image information in the K-th image display period) and the pixel corresponding to the position newly written by the pen-type light irradiation device (description image information in the K + 1-order image display period) ) And black display. That is, an image written by the user on the display content on the previous screen is obtained.

  When the K + 1st order image display period ends, the K + 1st order information collection period starts next. As before, the position of the pen-type light irradiation device is specified during this period (FIG. 14- (6)). Based on this position information, the control unit creates description image information for the next K + 1st order image display period (FIG. 14- (7)). In the example of FIG. 14, since the pen-type light irradiation device has moved between the K-order image display period and the K + 1-order image display period, the image information described in the K + second-order image display period is a line (FIG. 14- (7 )). The thus obtained K + secondary description image information and K + secondary display image information (FIG. 14- (9), in this example, K + 1st order display image information and K + secondary display image information are the same) are combined to obtain a K + secondary image. A display image of the display period is produced (FIG. 14- (8)), and it is displayed in the K + secondary image display period. Similarly, the image display period and the information collection period are alternately repeated, and handwriting input to the functional plane proceeds.

  FIG. 15 is a perspective view illustrating a specific example of an electronic apparatus using the electro-optical device according to this embodiment. FIG. 15A is a perspective view illustrating a so-called electronic book. The electronic book 1000 includes a book-shaped frame 1001, a cover 1002 that can be rotated (openable and closable) with respect to the frame 1001, an operation unit 1003, and the electro-optical device according to the present embodiment. The display unit 1004 is provided. FIG. 15B is a perspective view illustrating so-called electronic paper. The electronic paper 1200 includes a main body unit 1201 configured by a rewritable sheet having the same texture and flexibility as paper, and a display unit 1202 configured by the electro-optical device according to the present embodiment. Note that the range of electronic devices to which the electro-optical device can be applied is not limited to this, and includes a wide range of devices that utilize changes in visual color tone accompanying the movement of charged particles. For example, in addition to the above-described devices, those belonging to real estate such as wall surfaces to which an electro-optical device is bonded, and those belonging to moving bodies such as vehicles, flying objects, and ships are also applicable.

  As described above, when the first transistor is turned off, the electro-optical device according to the present embodiment scans the second transistor and sequentially turns it on. In this state, the first transistor is moved to the pen-type light irradiation device. The off-current is generated or increased by applying relatively strong light. Then, by detecting the off-current through the signal line, the first transistor having a large off-current can be grasped. The designated position on the screen can be detected based on the position of the first transistor having a large off-state current. As described above, an electro-optical device capable of detecting the position on the screen can be realized with a simple configuration as compared with the related art. Moreover, according to this structure, the light irradiation to the first transistor can be performed from the transparent first substrate side. At this time, since the light incidence to the second transistor is blocked by the light shielding film, the operation control of the second transistor becomes easier. At this time, the display state of the electro-optic element can be visually recognized from the pixel electrode side by using a transparent conductive film as the pixel electrode in contact with the circuit layer (that is, on the first substrate side).

  The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, the above-described charged state or colored state (white, black) of the electrophoretic particles is an example, and the present invention is not limited to this. Moreover, numerical values such as voltage values also mean specific examples, and are not limited thereto.

  In the above-described embodiment, the electro-optical device is taken as an example of the electro-optical device, but the scope of application of the present invention is not limited to this. By replacing the electro-optical element in the above embodiment with a liquid crystal element, a liquid crystal device as one aspect in which the present invention is embodied can be obtained. Similarly, by replacing the electro-optic element with an electrochromic element, an electrochromic device as one aspect in which the present invention is embodied can be obtained.

(Example)
FIG. 6 is an example of a plan view showing a wiring structure of a pixel. The cross-sectional view shown in FIG. 5 generally corresponds to the direction of line III-III shown in FIG. As shown in the figure, the light shielding film 64 is provided on the lower layer side of the semiconductor film 72 and in a portion of the semiconductor film 72 constituting the second transistor 42, more specifically, at a position overlapping with at least the channel formation region. It has been. The semiconductor film 72 is shared by the first transistor 40 and the second transistor 42. The first scanning line 10 and the second scanning line 12 are provided on the upper layer side than the semiconductor film 72. Further, a signal line 14 and another wiring 11 are provided on the upper layer side. As illustrated, the wiring 11 is connected to the semiconductor film 72 (portion corresponding to the second transistor 42) through a contact hole, and is connected to the first scanning line 10 in the (i-1) th row. FIGS. 7 to 11 show a process for forming these wirings and the like. A formation process is demonstrated easily along each figure. In addition, description is abbreviate | omitted about a transparent electrode and the insulating film which exists between each wiring. First, a light shielding film 64 is formed at a predetermined position on the first substrate 60 (FIG. 7). Next, a semiconductor film 72 is formed at a position where the light shielding film 64 partially overlaps (FIG. 8). The semiconductor film 72 is obtained, for example, by forming a polysilicon film and patterning it into an island shape. Next, the first scanning line 10 and the second scanning line 12 are formed above the semiconductor film 72 (FIG. 9). These are obtained, for example, by forming a conductive film such as aluminum and then patterning. Next, a contact hole is formed at a predetermined position of an insulating film (not shown) (FIG. 10). Next, the signal line 14 and the wiring 11 are formed above the semiconductor film 72 (FIG. 11). These are obtained, for example, by forming a conductive film such as aluminum and then patterning.

  Next, a configuration example of a pen-type light irradiation apparatus suitable for use in the electro-optical device 1 of the present embodiment will be described. Here, the pen-type light irradiation device refers to a device having the same shape as a general pen and capable of emitting strong light from one end side thereof. Note that the device for handwriting input to the apparatus is not limited to this, and any lighting device that emits small and strong light may be used.

  FIG. 12 is a schematic diagram illustrating a configuration example of a pen-type light irradiation device. In FIG. 12, a pen-type light irradiation device of one configuration example is shown in a plan view, and one end (pen tip) is partially shown in a sectional view. The illustrated pen-type light irradiation device 3 includes a reflecting mirror 302, an LED light source 304, and a lens 306 on one end side of a main body 300. The light emitted from the LED light source 304 enters the lens 306 directly and as reflected light by the reflecting mirror 302. The incident light is collected at the focal point 308 by the lens 306. The light collected at the focal point 308 then diverges. The LED light source 304 is an example, and other light sources may be used. According to such a pen-type light irradiation device 3, it is possible to irradiate the surface of the first substrate 60 of the electro-optical device 1 with light having high illuminance at the focal point 308.

  Here, the conditions necessary to enable writing with the pen-type light irradiating device 3 will be considered regardless of the sunlight illuminance due to external weather such as rainy weather or fine weather. The sunlight illuminance on a rainy day or a dark day is approximately 2000 lux, and the clear sunlight illuminance is approximately 100,000 lux. On the other hand, the off-state current of the thin film transistor is proportional to the amount of light irradiation. The off-current at 0 lux is about 1 pA (picoampere), about 10 pA at 10,000 lux, and the off-current is about 100 pA under clear sunlight (illuminance 100,000 lux). In addition, when a high-intensity LED that currently exists is used, the light illuminance at a beam diameter of 10 mm is about 100,000 lux. Therefore, when the beam diameter is reduced to 1 mm by the lens 306, the illuminance at the focal point 308 is about 10 million lux. That is, at the focal point 308, an illuminance of about 100 times the sunlight illuminance at the time of fine weather can be obtained. The off-state current of the thin film transistor with respect to the light illuminance at the focal point 308 is about 10000 pA, and this value is sufficient to determine the presence or absence of light irradiation. Since the light emitting part of the LED light source is usually about 0.2 mm × 0.2 mm, the lens 306 can collect light up to this size. With this size, the illuminance easily exceeds 100 million lux, and more than 1000 times that of clear sunlight, so the off-state current of the thin film transistor also becomes more than 1000 times. Therefore, the writing with the pen-type light irradiation device 3 is possible even in fine weather.

この計算式に、人間が自然にペンを持つ時の角度θの範囲である60°〜80°を代入すると、距離Ｌの好適範囲は、１．０１５ｄ≦Ｌ≦１．１５５ｄとなる。従って、この値が実現されるような焦点距離を有するレンズ３０６を用いることが望ましい。 Here, a preferred range of the distance from the pen tip of the pen-type light irradiation device 3 to the focal point 308 will be described with reference to FIG. Assuming that the distance from the pen tip to the focal point 308 is L and the thickness of the first substrate 60 is d, the distance L from the pen tip to the thin film transistor is represented by the following equation as shown in the figure.

Substituting 60 ° to 80 °, which is the range of the angle θ when a human naturally holds a pen, into this calculation formula, the preferable range of the distance L is 1.015d ≦ L ≦ 1.155d. Therefore, it is desirable to use a lens 306 having a focal length that realizes this value.

(Technical thought)
In many cases, a display unit of an electronic apparatus that can replace a function of a conventional paper medium such as a so-called electronic paper or an electronic book is configured using an electrophoretic device. Such conventional electrophoretic devices are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2005-24864, 2005-283820, and 2005-84343. However, conventional electronic paper and the like perform display based on data (for example, image data such as books and photographs) stored in a memory in advance. In other words, electronic paper or the like is only used for display purposes, and allows the user to write a memo or underline freely in the display image, or to perform processing such as designating a desired position in the image. It was difficult to make up. As an example, it is conceivable to provide a touch sensor on the display surface of electronic paper or the like, but in this case, the configuration becomes complicated, and further improvements are made from the viewpoint of size reduction and weight reduction such as thickness. There is room. Such a problem is not limited to the electrophoretic device, but is common to liquid crystal devices, electrochromic devices, and the like. Therefore, an electro-optical device and an electronic apparatus that can detect a designated position on the screen with a simpler configuration are desired.

The electrophoresis apparatus according to the present invention is
A plurality of first scan lines;
A plurality of second scanning lines equal in number to the first scanning lines and arranged in parallel with the first scanning lines;
A plurality of signal lines arranged crossing each of the first scanning line and the second scanning line;
An electro-optical device comprising a plurality of pixel portions arranged in a matrix in each intersection of the first scanning line, the second scanning line, and the signal line,
Each of the pixel portions located in i rows and j columns (i and j are both natural numbers) includes a first transistor, a second transistor, and a pixel electrode,
The gate of the first transistor is connected to the first scanning line in the i-th row, and one source / drain is connected to the signal line in the j-th column,
The gate of the second transistor is connected to the second scanning line in the i-th row, and one source / drain is connected to the other source / drain of the first transistor,
The pixel electrode is connected to the other source / drain of the first transistor;
This is an electro-optical device.

  According to such a configuration, when the first transistor is turned off, the second transistor is scanned and sequentially turned on, and in this state, the first transistor can be relatively compared with a pen-type instrument that can irradiate light from one end. Off-current is generated or increased by applying strong light. Then, by detecting the off-current through the signal line, the first transistor having a large off-current can be grasped. The designated position on the screen can be detected based on the position of the first transistor having a large off-state current. That is, according to the present invention, it is possible to realize an electro-optical device in which a configuration for position detection is incorporated in the panel, and a simple configuration can be realized as compared with the conventional technique.

  In the electro-optical device, it is preferable that the other source / drain of the second transistor is connected to the first scanning line in the (i−1) th row.

  Thereby, the number of signal lines can be reduced.

  In the electro-optical device, the pixel portion preferably includes a pixel electrode and a common electrode, and an electro-optical material disposed between the pixel electrode and the common electrode. Here, the “electro-optical material” refers to a material that causes an optical state change due to an electrical stimulus (voltage, current, etc.) from the outside, and includes, for example, an electrophoretic material, a liquid crystal material, and an electrochromic material.

  Thus, an electrophoretic device, a liquid crystal device, or an electrochromic device in which a configuration for position detection is incorporated in the panel is obtained.

  The electrophoretic device preferably further includes a storage capacitor connected between the other source / drain of the first transistor and the first scanning line in the (i−1) th row.

  Thereby, the display contrast can be increased. In addition, the aperture ratio of the pixel can be increased by being connected to the first scanning line in the (i-1) th row.

The electro-optical device includes a first substrate and a second substrate,
The first substrate is transparent;
The first scan line, the second scan line, the signal line, the first transistor, and the second transistor are disposed on the first substrate to form a circuit layer,
The pixel electrode is formed of a transparent conductive film on the circuit layer,
A light shielding film is disposed between the first substrate and the second transistor;
The common electrode is formed on the second substrate;
Sandwiching an electro-optic material between the first substrate and the second substrate;
It is preferable.

  According to such a configuration, light irradiation to the first transistor can be performed from the transparent first substrate side. At this time, since the light incidence to the second transistor is blocked by the light shielding film, the operation control of the second transistor becomes easier. At this time, the display state of the electrophoretic element can be visually recognized from the pixel electrode side by making the pixel electrode in contact with the circuit layer (that is, the first substrate side) a transparent conductive film.

  In the above electro-optical device, the storage capacitor is preferably included in the circuit layer.

Further, the storage capacitor includes the pixel electrode and the storage capacitor electrode, and a storage capacitor dielectric film sandwiched between the pixel electrode and the storage capacitor electrode,
The pixel electrode, the storage capacitor electrode, and the storage capacitor dielectric film are preferably transparent.

  Thereby, the visibility of the display from the first substrate side is improved.

  In the electro-optical device, it is preferable that the light-shielding film is provided at a position overlapping the active region of the second transistor. Here, the “active region” means a channel formation region, a drain region in contact with the channel formation region, and a source region in contact with the channel formation region. The light shielding film is preferably provided at a position that does not overlap with the active region of the first transistor.

  By blocking light incidence on at least the active region, it is possible to avoid a considerable adverse effect on the second transistor.

The electro-optical device described above is
A first scan driver connected to the first scan line;
A second scanning driver connected to the second scanning line;
A signal line driver connected to one end of the signal line;
A switching circuit that is connected between the signal line and the signal line driver and switches between conduction and non-conduction between the signal line and the signal line driver;
A sense amplifier connected to the other end of the signal line;
It is preferable to comprise.

  According to this configuration, it is possible to achieve both control for position detection on the screen and control for image display by the electrophoretic element with a relatively simple configuration.

More preferably, the electro-optical device described above is
A controller for supplying a control signal to each of the first scanning driver, the second scanning driver, the signal line driver, the switching circuit, and the photosensor signal readout circuit;
A storage unit connected to the control unit;
Further comprising
The control unit stores data read by the photosensor signal readout circuit in the storage unit.

  When the control unit performs information processing using the read data stored in the storage unit, the designated position on the screen can be specified and reflected in subsequent processing. In addition, the operations of the drivers, the switching circuit, and the photo sensor signal readout circuit can be managed by the control unit.

  As a preferable aspect of the information processing using the read data, the control unit updates the image data stored in the storage unit based on the read data, and sends a control signal corresponding to the image data to the control signal. Supply to signal line driver.

  As a result, an image corresponding to the position detection result on the screen can be overwritten on the current image.

As a more preferred embodiment,
An input unit connected to the control unit;
The control unit controls the switching circuit to turn off the signal line and the signal line driver when a predetermined operation instruction is input using the input unit, and the photo sensor signal readout circuit Is activated.

  Accordingly, it is possible to switch between an image display mode and a manual input mode (for example, a mode for performing image writing as described above) in accordance with an operation instruction using the input unit.

  The electro-optical device according to the present invention as described above is preferably used as a display unit of an electronic apparatus such as an electronic paper or an electronic book.

  Accordingly, an electronic book or the like having both a display function by the electro-optical device and an instruction input function on the screen can be realized with a simpler configuration.

1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment. 1 is a block diagram illustrating a configuration of an electro-optical device according to an embodiment. It is a circuit diagram which shows the detailed structure of a pixel. It is a circuit diagram which shows the detailed structure of a pixel. 2 is a partial cross-sectional view schematically showing a cross-sectional structure of a pixel of an electro-optical device. FIG. It is a fragmentary top view shown about the wiring structure of a pixel. It is a top view explaining formation processes, such as pixel wiring. It is a top view explaining formation processes, such as pixel wiring. It is a top view explaining formation processes, such as pixel wiring. It is a top view explaining formation processes, such as pixel wiring. It is a top view explaining formation processes, such as pixel wiring. It is the schematic explaining the structural example of pen-type light irradiation apparatus. It is a figure explaining the suitable range of the distance from the pen point of a pen-type light irradiation apparatus to a focus. It is a figure explaining handwriting input mode. It is a schematic perspective view which illustrates an electronic device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 3 ... Pen type light irradiation apparatus, 10 ... 1st scanning line, 11 ... Wiring, 12 ... 2nd scanning line, 14 ... Signal line, 16 ... Pixel, 18 ... 1st scanning line selection circuit, DESCRIPTION OF SYMBOLS 20 ... 2nd scanning line selection circuit, 22 ... Display signal supply circuit, 24 ... Switching circuit, 26 ... Sensor signal readout circuit, 28 ... Control part, 30 ... Memory | storage part, 32 ... Input part, 40 ... 1st transistor, 42 ... second transistor 44 ... electro-optic element 46 ... retention capacitor 48 ... pixel electrode 50 ... common electrode 52 ... electro-optic material 60 ... first substrate 62 ... circuit layer 64 ... light-shielding film 66 ... Electro-optical element layer, 68 ... second substrate, 70 ... insulating film, 72 ... semiconductor film, 74 ... retention capacitor first electrode, 75 ... wiring, 76 ... wiring, 78 ... insulating film, 80 ... insulating film, 82 ... insulating Membrane 84 ... Insulating membrane 300 ... Main body 302 ... Reflector 3 4 ... light source, 306 ... lens, 308 ... focus, 1000 ... ebook, 1001 ... frame, 1002 ... cover, 1003 ... operation unit, 1004 ... functional plane, 1200 ... electronic paper, 1201 ... body part, 1202 ... functional plane

Claims (19)

In an electro-optical device having an image display period and an information collection period,
The electro-optical device has a panel unit and a data processing unit,
The panel portion includes a first substrate, a second substrate, and an electro-optic material,
The electro-optic material is sandwiched between the first substrate and the second substrate;
On the first substrate, a plurality of first scanning lines, a plurality of second scanning lines arranged in parallel to the first scanning lines, and a plurality of intersecting the first scanning lines and the second scanning lines A signal line and a pixel disposed at an intersection of the first scanning line and the second scanning line and the signal line;
A plurality of the pixels are formed in a matrix on the first substrate,
Each of the pixels located in i rows and j columns (where i and j are natural numbers) each include a first transistor, a second transistor, and a pixel electrode;
The gate of the first transistor is connected to the first scanning line of the i-th row, and one of the source or drain of the first transistor is connected to the signal line of the j-th column,
The gate of the second transistor is connected to the second scanning line of the i-th row, one of the source or drain of the second transistor is connected to the other of the source or drain of the first transistor,
An electro-optical device, wherein the other of the source and drain of the first transistor and the pixel electrode are connected.   The electro-optical device according to claim 1, wherein the other of the source and the drain of the second transistor is connected to a reference power source.   2. The electro-optical device according to claim 1, wherein the other of the source and the drain of the second transistor is connected to the first scanning line in the (i−1) th row.   The electro-optical device according to claim 2, further comprising a storage capacitor between the other of the source and the drain of the first transistor and the reference power source.   4. The electro-optical device according to claim 3, further comprising a storage capacitor between the other of the source and the drain of the first transistor and the first scan line in the (i−1) th row.   The first substrate is transparent, a common electrode is formed on the second substrate, the pixel electrode is formed of a transparent conductive film, and a light shielding film is formed between the first substrate and the second transistor. The electro-optical device according to claim 1, wherein the electro-optical device is disposed. The first substrate is transparent, a common electrode is formed on the second substrate, the pixel electrode is formed of a transparent conductive film, and a light shielding film is formed between the first substrate and the second transistor. Is located,
The storage capacitor comprises a storage capacitor first electrode, a storage capacitor second electrode, and a storage capacitor dielectric film sandwiched between the storage capacitor first electrode and the storage capacitor second electrode, 6. The electro-optical device according to claim 4, wherein both the storage capacitor second electrode and the storage capacitor dielectric film are transparent.   The electro-optical device according to claim 7, wherein the pixel electrode is the storage capacitor second electrode.   9. The electro-optical device according to claim 6, wherein the light shielding film is provided at a position overlapping with an active region of the second transistor.   The electro-optical device according to claim 6, wherein the light shielding film is provided at a position that does not overlap with an active region of the first transistor.   On the first substrate, a first scanning line selection circuit connected to the first scanning line and having a function of selecting a specific first scanning line from a plurality of first scanning lines, and the second scanning line A second scanning line selection circuit having a function of connecting and selecting a specific second scanning line from a plurality of second scanning lines; and a signal line connected to one end of the signal line and connected to each of the plurality of signal lines A display signal supply circuit having a function of supplying a unique display signal, and a sensor having a function of reading a sensor signal unique to each signal line connected to the other end of the signal line and output from each of the plurality of signal lines The electro-optical device according to claim 1, wherein a signal readout circuit is formed. The data processing unit includes an input unit, a control unit, and a storage unit,
The input unit has a function of supplying display image information input from the outside to the control unit or the storage unit,
The control unit has at least a function of controlling the first scanning line selection circuit, the second scanning line selection circuit, the display signal supply circuit, the sensor signal readout circuit, and the storage unit.
The electro-optical device according to claim 11, wherein the storage unit has a function of storing the display image information and description image information based on the sensor signal.   The control unit has a function of creating a new display image using the display image information and the description image information, and supplying the new display image to the display signal supply circuit as a new display signal. The electro-optical device according to claim 12.   14. A switching circuit for switching between conduction and non-conduction between the signal line and the display signal supply circuit is provided between the signal line and the display signal supply circuit. The electro-optical device according to any one of the above.   The switching circuit sets the signal line and the display signal supply circuit in a conductive state during the image display period, and sets the signal line and the display signal supply circuit in a non-conductive state during the information collection period. The electro-optical device according to claim 14.   16. The electro-optical device according to claim 1, wherein the electro-optical material is an electrophoretic material.   16. The electro-optical device according to claim 1, wherein the electro-optical material is a liquid crystal material.   The electro-optical device according to claim 1, wherein the electro-optical material is an electrochromic material.   An electronic apparatus comprising the electro-optical device according to claim 1.

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